Sorry, but I am going to agree with Tony here. Ubuntu is clearly associated with an operating system that based on Linux (and related technologies) that is 99% free software. The current use of Ubuntu is largely by LoCo teams promoting said operating system. There is also use by commercial interests promoting their software as running on Ubuntu or as selling computers running Ubuntu. Both of these latter uses are descriptive and explicitly allowed under most copyright law.
Ubuntu One is completely at a tangent to that. It is a service that can be used in Ubuntu. If we are going to tie Ubuntu into Ubuntu One, then we are violating our own stated promise of keeping Ubuntu all free software.
So basically, yes, Canonical owns the Ubuntu trademark. However, it is accountable to the larger Ubuntu community for use of that trademark and I think this use violates that trust and accountability.